Shawn Colvin
Sea Of Bees
Shelby Lynne
Scarlett Johansson
Sandy Denny
Kris Delmhorst
Ren Harvieu
Aimee Mann
Amy LaVere
Julia Stone
Anna Calvi
Auf Der Maur
Cerys Matthews
Eddi Reader
Emily Haines
Emma Pollock
Emmy The Great
Fiona Apple
Gemma Hayes
Grimes
Heidi Talbot
Inara George
The Indigo Girls
Jane Siberry
Jesca Hoop
Joan As Police Woman
Karen Ann
Judie Tzuke
Kate Rusby
Ladyhawke
Laura Marling
Lisa Hannigan
Luik
Lykki Li
Maria McKee/Lone Justice
Mary Epworth
Mechanical Bride
Natalie Merchant
Nero Case
Niki & The Dove
Oh Laura
Patty Griffin
There’s more, but those should keep you ticking over for a while.
There’s bands like Howling Bells with great female singers, Emily Haynes is Metric’s lead singer, so check them out as well.
Oh, and there’s Tanya Donelly, and her band Belly.
(I’ve left off several that have already been mentioned above, like Kristin Hersch)